Apparatus for applying coatings to curved surfaces



APPARATUS FOR APPLYING commas TO CURVED SURFACES Filed March 4, 1957 A. G. FARRIES May 12, 1959 4 Sheets-Sheet 1.

INVENTOR Melanoma Gokoou Fumes ATTORNEY May 12, 1959 AMG. FARRIES APPARATUS FOR APPLYING COATINGS TO CURVED SURFACES r 4 Sheets-Sheet 2- Filed March 4, 1957 INVENTOR ALsmNoaR GQRDQN Fumes swam, (5&

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ATTORNEY y 1 A. G. FARRIES 2,885,998

APPARATUS FOR APPLYING commas TO CURVED SURFACES Filed March 4, 1957 4 Sheets-Sheet 3 ATTORNEY May 12, 1959 A. G. FARRIES APPARATUS FOR APPLYING COATINGS TO CURVED SURFACES Filed March 4, 1957 4 Sheets-Sheet 4 ,INVENTQR ALEXANDER Gokbou Fumes QTTORN EY United States Patent a APPARATUS FOR APPLYING COATINGS TO CURVED SURFACES Alexander Gordon Farries, Luton, England, assignor to p D. Napier & Son Limited, London, England, a company of Great Britain Application March 4, 1957, Serial No. 643,743

Claims priority, application Great Britain March 8, 1956 8 Claims. (Cl. 118-323) This invention relates to apparatus for applying a coat- ,ing to a curved surface, and is particularly concerned with the problem of ensuring uniform thickness, and other.

that its rate of traverse across the surface should be approximately constant. Moreover the attitude of the gun in relation to the surface should be constant and preferably normal to the part of the surface being sprayed.

constant distance from the surface to be coated and also According to the invention therefore apparatus for applying a coating to a curved surface by means of a spray gun comprises at least one curved contour plate, corresponding to the profile of the curved surface in a selected plane, means for moving the spray gun round the contour plate, and means for causing the gun to traverse relative l to the surface in a direction transverse to the plane of the contour plate.

The spray gun may be. lockedin position relative to the contour plate, while the traversing movesment takes place, or both movements may occur simultaneously.

The invention is thus readily applicable to surfaces of single curvature, in which the profile of a cross section through. the surface is unchanged or substantially unchanged along the length of the surface normal to such cross section. According to one preferred feature of the invention therefore the apparatus comprises two curved contour plates arranged in parallel planes, a beam supported at either end on the contour plates by rollers or the equivalent arranged to locate the ends of the beam in the planes 'of the plates,-and means for traversing the spray gun longitudinally along the beam.

Preferably the apparatus includes a pair of rotary indexingmembers at either end of the beam mounted on a common shaft or arranged to rotate together, and engaging a pair of racks, chains or the equivalent fixed ad- "jacent to each of the contour plates, and means for rotating the two indexing members in synchronism so as to move the beam bodily around the plates, each end of the beam moving an equal distance.

In such case the apparatus will preferably include continuously driven traversing mechanism associated with the beam, and means for engaging the spray gun or a {carriage therefor with the traversing mechanism, to cause the spray gun to be traversed along the beam.

According to a preferred feature of the invention the traversing mechanism comprises an endless chain or the equivalent passing over a sprocket at opposite ends of the beam, and means for clutching the spray gun or its ,parallel to one another.

which the resistance coating is to be applied is mounted Patented May 12, 1959 carriage on to one side or the other of the endless chain to cause the gun to traverse in either direction.

Moreover the apparatus will preferably include cam means on the beam and On the spray gun or its carriage arrangedto cooperate automatically to reverse the direction of traverse when the gun reaches one end of the beam.

When applied to a surface of tapered profile, such, as the leading edges of aircraft wings or tailplanes, it is not satisfactory to use two con-tour plates of the same profile and merely to traverse the gun longitudinally between the plates. This would cause variations in the distance between the gun and the surface as it traverses along the surface and also some variations in the attitude of the gun relative to the surface.

. According to a preferred feature of the invention therefore the apparatus includes two contour plates of differ: ent contours, corresponding to the profile of the surface at two different longitudinal stations and means for adjusting the attitude of the spray gun in relation to the beam automatically as the gun is caused to traverse along the beam, so as to maintain aconstan-t angle between the gun andthe part of the surface being sprayed.

The invention may be performed in various different ways but one specific embodiment will now be described by Way of example as applied particularly to a spraying rig for applying a metallic electrical resistance pattern to aircraft surfaces.

In the accompanying drawings Figure l is a front elevation ofthe spraying rig,

Figure 2 is an end elevation of the rig,

Figure 3 is a front elevation of the spray gun and beam on an enlarged scale,

Figure 4 is a plan view of the spray gun and beam corresponding to Figure 3, and Figure 5 is a fragmentary end sectional view showing the pivotal mounting of the spray gun.

This example is applicable to the leading edges of wing or. tail plane, or like surfaces, and in particular to tapered surfaces. The basic structure of the rig comprises two framework units 10, 11, each supporting a curved contour plate 12, 13, in a vertical plane, the two plates being The tailplane section 14 to between the plates 12, 13, with the leading edge livertically downwards, and the contour plates are specifically designed to conform to the profile of the leading edge of the tail plane at the two corresponding longitudinal stations such that the distance between any point on the contour plates and the surface of the tailplane, in a direction normal to its surface, is substantially constant around the whole length of the profile of the plates.

Mounted between the two contour plates is a beam 16 having at its ends a pair of brackets 17, 18, each of which carries a pair of rollers 19, 20, engaging the inner surface of the respective contour (12 or 13). One of these brackets 17 is rigidly connected to the beam 16,

while the other bracket 18 is pivotally connected to a flange 21 on the beam by means of a spherical bearing 22. Thus the two brackets can swivel relative to one another to allow for the different angular attitudes of the corresponding parts of the contour plates 12 and 13.

An indexing shaft 25 running the length of the beam. is provided at each end with sprockets 26, 27, which engage fixed:chains 28, 29 lying on the outer edges of the contour plates, and an indexing hand wheel 30 on the beam, geared to the indexing shaft 25 through worm gears 31, 32, enables the beam to be indexed around the plates, and hence round the leading edge of the tail plane, each end of the beam moving the same distance around the respective plate. It will be seen that the sprockets 26, 27, act in opposition to the rollers 19, 20,

3 so as-to controlthe'position and angular attitude of each of the brackets 17, 18.

The beam 16 carries a pair of parallel guide tubes 35, 36,on which is arranged a sliding carriage'37, on which is pivotally mounted a saddle 38,'sup'po'rting-a spray gun 39. The pivotal axis of 'the connection between the saddle 38 and the carriage 37, which is formed by t-wo pins 40, is coincident with the centre of'the spherical joint 22, and also with the'eifective points of contact between the two sprockets 26, 27, and the respective fixed chains 28, 29. Thus the spray gun 39 can pivot about this longitudinal axis, which is the efiective centreline of the beam.

Iii-addition the two brackets 17, 18, are provided with extensions 41, 42, having spherical joints 43, 44'a't their extremities, and'between these joints is mounted a guide tube 45, whose angular "attitude will differ from. that of the beam 16, as determined by the'differentangular attitudes of the brackets 17, '18. The spray gun 'and its saddle 38 are provided with rollers '46, '47, which respectively engage on opposite sides of the guide tube 45, so that the instantaneous attitude of the gun, as the-carriage 37 traverses along the beam, is determined by :the position of the guide tube.

It will be seen that since the attitude of the two brackets 17, 18 is determined by the contour plates 12, 13, the attitude of the gun will be maintained automatically so that the axis of the spray is normal to the part of the surface of the wing which is being sprayed at any instant.

The spray gun is of the known kind having automatic feed, providing constant spray delivery. The gun will not therefore be described in detail but :in general it includes a gas burner 52, and electric motor 51, arranged to feed a metal wire 53, into the flame of the burner, and a compressed air jet arranged to blowthe molten metal in finely divided form through the nozzle 50 on to the surface to be coated. The supply of fuel, compressed air and electric current is arranged through flexible leads 54 connected to the gun from a supply point 55 on the stationary part of the structure, while the metal wire 53 is supplied from a drum 56 on the floor beneath -the beam.

The carriage 37 supporting the gun is arranged to be traversed automatically along the guide .tubesv35, 36and to this end the beam is provided at either end with a sprocket 60, 61, on which is mounted an endless chain '62, this chain being driven continuously through aigeared drive 63 at the end of the beam which is in turn .connected to an external motor 64 on the supporting structure through a flexible drive which includes a telescopic shaft 65 having universal couplings at opposite "ends, to permit the drive to be maintained as the beam is moved round the contour plates.

The electrical resistance pattern to be applied to the surface will be in the form of strips or .paths parallel to the leading edge, and each strip may be applied either Thus the carriage 37, supporting the. gun 39, will include means for clutching .the carriage to one side or the other of the continuously driven chain 62 ton the beam.

In this example the clutching mechanism comprises a transverse slide 66 having dogs 67, 68, which are "arranged to engage selectively 'with to i Sides Df me chain 62. The slide 66 has at one end a double ram 4 formation 69, which isactuated automatically by inclined cams or trip members 70, 71, at opposite ends of the beam.

What I claim as my invention and desire to secure by Letters Patent is:

1. Apparatus for applying a coating to a curved surface bymeans of a spray gun comprising-two curved contour plates arranged in parallel planes, each plate corresponding to the profile of the curved surface in a selected plane, a beam, a spray gun mounted on 'said beam, rollers supporting said beam at its ends on said contour plates and arranged to locate the ends of said beam in the planes of said plates, means for traversing the spraygun longitudinally along the beam, and means [for moving the two ends of the beam around the contour plates.

2. Apparatus as claimed in claim 1 in which the means "for moving the two ends of the beam around the-contour plate comprise a pair of rotar'ypinions one at each end of said beam arranged to rotate together, a'pair o'f .rack means fixed adjacent to each of said contour plates and engaged by said pinions, and means for rotatingsaid two pinions in synchronism.

3. Apparatus as claimed in claim 1 in which the means for traversing the spray gun include continuously driven traversing mechanism associated with said beam, and means adapted to engage said spray gun with said trav ersing mechanism, to cause said spray gun to be traversed along said beam.

4. Apparatus as claimed in claim 3 in which said traversing mechanism comprises an endless chain, a sprocket at opposite ends of said beam over which said *chain passes, and means for clutching said spray gun on :to

either side of said endless chain to cause said spray gun nism.

7. Apparatus as claimed in claim 1 for use .in treating a surface of tapered profile, including two contour plates of dilferent contours, corresponding to the profile of the surface at two dilferent longitudinal stations, and means for adjusting the attitude of said spray gun automatically in relation to said beam as said spray gun :is traversed along said beam, so as to maintain a constant :angle between said spray gun and the part of said surface being sprayed.

8. Apparatus as claimed in claim 7, in which the means for adjusting the attitude of the spray gun comprise brackets at opposite ends of said beam, capable of relative pivotal movement-about the longitudinallaxis of said beam, each bracket engaging the respective contour plate so as to be positioned angularly thereby, and a guide member connected between said two brackets, said spray gun being so supported that it is capable of pivoting also about the longitudinal axis of said beam, and being .arranged to engage said guide member such that its angular attitude is determined thereby, and automatically adjusted as said spray gun traverses along the beam.

References Cited in the file of this patent UNITED STATES PATENTS Brackett June 15, 1937 Verba June 24, 1958 

